1. Field of the Invention
The invention relates to a fiber optic based interferometer sensing device operable to sense a disturbance along a signal path and provide a location of the event.
2. Description of Related Prior Art
U.S. Pat. No. 6,459,486 discloses a single fiber Sagnac fiber sensing system. The system includes a generally broadband, low coherence length light source that injects light into a fiber beam splitter that is used to generate counter propagating light beams in a Sagnac loop. The loop includes two facing fiber beam splitters connected together at differing length inner legs, with one of the output legs of the second beam splitter usually being connected to an optical fiber that ends with a phase modulator followed by a mirror. Environmental effects at the optical fiber impress relative phase differences between the counter propagating light beams, which are detected from an interferometric signal that results therefrom.